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K L TATMAN FLOTATION APPARATUS Pwmi? Filed April 14, 1949 Oct. 21, 1952 pulp.

Patented Oct. 21, 1952 UNITED STATES PATENTOFFICE FL OTATION APPARATUS Kenneth L. Tatman, Leadville, 0010., assignor to ResurrectionMining Company, Leadville, 0010., a corporation of Delaware Application April 14, 1949, Serial No. 87,437,

4 Claims.

This invention relates to froth flotation and has for its object the provision of an improved flotation cell. More particularly, the invention is concerned with the agitation of the pulp to disperse air bubbles and reagents in the pulp, and provides an improved impeller assembly and air supply means which effect a material saving in power and with equal or superior metallurvupper blades and an air duct connected thereto for supplyin air at a pressure preferably, above atmospheric pressure under the shroud. The

pulp forced downward carries air into contact with the pulp forced upward, resulting in a better and more economical dispersion of air and reagents within the pulp. In an especially advantageous embodiment of the invention, I provide a shroud having an upper covering part I and a depending annular skirt concentrically disposed with respect to the upper blades with ,the lower edge of the skirt advantageously arranged to overhang at least a part of the peripheral edges of the upper blades whereby the air supplied to the shroud enters the pulp stream of the upper blades and is broken into minute bubbles by the impinging pulp from the lower blades. The skirt of the shroud performs the important function of protecting the upper blades from the wearing action of the ulp, thereby greatly increasing their effective life. I

.prefer to supply air throu h the duct to the shroud under a pressure greater than atmospheric, as by means of a low press re blower, and to provide means to vary the air pressure in, accordance with the. particular operating V conditions.

I attribute the mate ial decrea e in horsepower necessary to o erate the impeller to the d rectional location of the impeller blades which force the pul from below upward and outward and the pulp from above and air from the shroud downward and outward. to two moving bodies of fluid meeting at a common plane resulting n such an action that the air is divided into ve y m nute bubbles. The pulp is not only effectively circulated and aerated but the rea ents are thoroughly dispersed within the entire mass of It is important that the impeller be other.

2 cated in a favorable part of the liquid pulp and the shroud placed quite close to the upper blades, as will later be explained.

In my presently preferred construction I rotate the impeller on a shaft mounted within a tubular member which supports the shroud in concentric spaced relation to the shaft and connectthe tubularmember to a source of air under pressure. l

These and other novel features of the invention will be better understood afterconsidering the following discussion taken in conjunction with the accompanying drawings, in which:

Fig. l is a side elevation, with parts removed, of a flotation cell embodying my invention;

Fig. 3 is an enlarged fragmentary view of the shroud and impeller;

Fig. 4 is a side view of the lower end of the impeller shaft;

Figs. 5 and 6 are plan views of the upper and lower impeller blades respectively, and

Figs. 7 and 8 are side views of the upper and lower impeller blades respectively.

The flotation machine illustrated in the drawings comprises a rectangular tank for receiving the pulp which may consist of any number of separate cells. The partition I divides the tank into two cells 2 and 3. The tank shown has a feed well 4 from which the feed of ore pulp enters the first well of the tank through the adiustable feed opening 5, the pulp flowing from the feed opening t rough cell 2, under partition I, and through cell. 3 to the dischargeopening 6. On the discharge end of the tank is a rectangular shaped box '1 containing a partition 8 adjustable in height by the adjusting member 9. The tailings from the cell tank flow by gravity through the opening 5 and over the adjustable partition 6 to the bottom 1!! of the box from which it maybe pumped or carried by gravity to its next destination. Along one side of the cell tank is an adjustable weir l I over which the froth flows. A similar weir may be mounted on the opposite side. I

The improved air disseminating andreagent dispersing mechanism of my invention includes an impeller assembly consisting of an impeller ill having an u per set of blades 2| and a lower set of blades and a shroud 23 with air supply means it. The impeller is mounted on an upright shaft 22 and the two sets of blades are in vertical spaced relation with respect to each The im eller illustrated has four upper blades and two lower blades, although I may use various combinations of blades in either position. The upper blades are set to force the pulp downward while the lower blades are set to force pulp upward, both blades being inclined about.

30 from the horizontal and sloped oppositely. The impeller is preferably formed in two parts to facilitate casting and both parts are keyed to V the shaft andlheld-in; a fixed position by the set the lower part has an upwardly;extendinghub 21. These hubs are proportioned toigive proper. spacing to the blades which ordinarily should be around 4 inches. The shaftl l rotates'imthe anti-friction bearing 23 whichis held in the bearing housing 29. The bearing housing is supported by a super "structure 30 which rests upon;the?top of. the tank or many other suitable-support; .The shaft 24 is rotatedtby; the .belt 32 and the connected motor-33.

. .Theairshaft or air duct. 34, for example'a steel ..or-.-iron-,pipe,,-is attachedat its .upper endto the .bearingrhousingcas. by means of the flange35.

,Air, is supplied .to the air-duct 34 by the. pipe .36 which .iseconnectedto the air manifold 31 and which is under an air pressurehigherthan atmospheric.pressure: suppliedby a low pressure end. ofcduct 34..in any -suitable ,mannerto facili- I tate rapid replace-mentiontheshroud duringopaerationaof .the-ce'lls. .Theshroud comprises a horizontally'disposed upper covering part in the storm. of vav disk. 4 Land, a depending .annu'lar. skirt 42. It will be noted that the disk isionly a short :distanceabove; the upper-blades 2| and thatthe depending. skirtcoverhangs-theupper blades for approximately half .their vertical depth, for example, approximately /2 inch below. the upper edge. Theshroud disk andskirt are spaced from .the; upper .blades sufliciently to provide suitable clearance, forexample, 3/2 inch.

. It .is-z advantageous toloc'ate the impeller, assembly-and shroudinthe lower half of the liq- ..,uid pulp. and .tdmaintainthe. upper level of liq- ...uid ifromw2. .to :10- inches, below the :level .of froth discharge. :Itis understood, of course, that the pulp. contains thBIJIBCBSSaI'Y', flotation reagents ito.result..in arrzappreciable depth offroth above rthe. level-.ofsl iquid maintained in the cell. -the irnpeller rotatedataxperipheral speed of approximately. 2100 feet per: minute and with impeller.bladesinclinedfrom the horizontal around .'30 ..a*verysintense agitation of, the. pulp results.

- Any number of similar cells may be used eache provided: with the impeller assembly described. .As the;:pulp--progresses from the first cell (2) t-o eachsucceeding cell (if more than one cell is ,required) it .issucceSsiVely:acted upon by. each impeller and circulated and aerated-simulta .neously. ..A concentrateis forcedv over the ad- .justable .weir, I l. .When,the .machine is being .,.operated, .no .pulp; is within the air duct 34. The --.fiuid leve1-within the cells. must be variable according tooperating conditions but is normally someplacebetween the level of the concentrate ..dis.charge weir I I and about. 10. inches. below.

. The inventionris,also. adaptable to flotation .acells provided with means. for the recirculation eof concentrates. Ilhe:invention contemplatesthe With use of an impeller, shroud and air duct or the type described to utilize air at atmospheric pressure.

The invention accomplishes an unpredicted 5 very material decrease in the power to effect the desired aeration and dispersion of the reagents. In one operation using a 50 cubic foot machine,

-. the horsepowerwas reduced about 65%. in comparison -with modern well-known: flotation machines for doing the same work. A decrease in 1 athe required power of from 35% to 55% is general.

The "invention eliminates the need for stationary *bafliesgfor.dispersion and the prevention of isrpulpswirlsr .fIEhe.,.greater proportion of the pulp .-..withinr.-each:cella is aerated. There are only two .parts. which ,are subject to any great amount of weartheshroud 23 and the impeller 20, both ofwhich are cheap to manufacture and can be replaced in a few minutes without stopping the plant. and whilethe pulp is,s,ti11,flowing through .ithecell. With, the possible exception ofthecellor cells. in which. concentrates. are being reecirculated,,the -imp,e1ler.canbe, easily changedlwithout 5 stopping the fiow.,..of,pulp through the circuit.

I claim:

1. The improvement ,in. flotation cells which comprises ..an.,impeller with. two sets ,ofibla'des spaced apart vertically and arranged in the cell .to rotate withinthe.liquidpulp,.theupper blades being set .to force. the pulp downward, ,the lower .bladesbeingrsetwto force the pulpupWardinto impinging contact with, the ,downwardly moving l p. .a. shroudoverthe upper bladesj' having a depending.. skirt ,concentrica1ly disposed with re- ..spect .to therupper bladea'andmeans for supply- ..ing. air. under pressureundergthe shroud which i drawn downward along with. the p1 1 lp by" the -upper blades.

'2. A flotation cell according 'to claim"l-which comprises an air duct connected-to-theshroud, .means for supplying air .under a pressure above the atmospheric pressureto the duct; andmeans to control; the volume'and pressure of airsup- .plied to the shroud.

53.. The improvement. in flotation cells which comprises ,.an impeller .with "upper and lower blades spacedapart Vertically and arranged in the, cellto rotate within the liquid pulp, the upper b.lades being set to, force the pulp downward, the lower blades beingset to force thepulp upward intojmpinging contact with the. downwardly .,moying,p.u1p,ashrcud over. the upper .b1ades ,and -laterally.disposed-.therearound...andmduct means forsupplying..airiunder the shroud ,at asufficient pressure to prevent entryof pulpinrthaduct rmeansduring operation of the cell. I

.. 4. .The, improvement in 1 .flotation 1. cells which comprises an impeller with upper .and lower .blades spacedapart vertically and.m Qunted on .annpright. shaftandarraneed to rotate within ..,the .liquid ,pulp,., the uppergblades being set to force the pulp downward, the lower bladesbeing setto force .thepulp upward anhairsduct surroundin -theshaft, .means, for supplyin airlinder .a I pressure. above Natmospherio pressure ,to

. theair due arshroud attached .to. t.he-air..du

-. in .opencommunication therewith. havin a sportion-.exten ding laterally ,from. the ,air duct which 7 is spaced. abovethe. upper. blades andian. annular .depending. .skirt which ,.at. least palitially ,sur-

rounds. theupper b.1ades,. whereby the.airienten sing .thershroudris drawn. downward along -with the .plupby, the. upper blades. andis brQkeninto 75...minute bubbles.by contact-with the .pulp moving REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Stanley Apr. 22, 1930 Number Number Name Date Tucker Feb. 20, 1940 Daman et a1. Feb. 4, 1946 Booth Dec. 30, I947 FOREIGN PATENTS Country Date Germany June 22, 1933 Germany Mar. 15, 1941 

